Smoke detector and signal for ducts



June 28, 1949. c. N. CAHUSAC I 2,474,221

SMOKE DETECTOR AND SIGNAL FOR DUCTS Filed Sept. 28, 1946 3 Sheets-Sheet1 3noentor:

(gram 170% Ma gi;

7 Gttorneg June 28, 1949. c. N. CAHUSAC SMOKE DETECTOR AND SIGNAL FORDUCTS 3 Sheets-Sheet 2 Filed Sept. 28, 1946 June 28, 1949. c. N. CAHUSACSMOKE DETECTOR AND SIGNAL FOR DUCTS 3 Sheets-Sheet 3 Filed Sept. 28,1946 1 (Ittotneg Patented June 28, 194? UNITED STATES PATENT OFFICESMOKE DETECTOR AND SIGNAL FOB DUCTS Clarence Noel Cahusac, Newark, N.J., assignor to C-O-Two Fire Equipment 00., Newark, N. .L, a corporationof Delaware Application September 28, 1946, Serial No. 700,051 8 Claims.(01. 177-311) control room-to insure immediate warning of fires andprompt action to extinguish them.

In general, the apparatus comprises means for producing a beam of light,means for conducting a stream of fluid, such as smoke, into said lightbeam, a photoelectric element of the generative type located withrespect to said beam and said fluid stream to receive light raysreflected from suspended matter in said fluid stream-anotherphotoelectric element located to receive light rays transmitted throughsaid fluid stream, means connecting said photoelectric elements in anelectric circuit whereby the photoelectric effects of thesecond-mentioned element oppose the photoelectric efiects of .thefirst-mentioned element, and an electrical responsive means, such as arelay or Sensitrolf in said circuit for controlling the production of anaudible or visible signal.

Means also is included for varying at will the extent of exposure of thesecond-mentioned photoelectric element to the light rays. With thisarrangement, by adjustment of the means for varying the extent ofexposure of the second-mentioned photoelectric'element to the lightrays, the effect of the light on the first-mentioned photoelectricelement may be balanced by the effect of the light on thesecond-mentioned photoelectric element whereby a steady and normalsetting of the electrical response device or Sensitrol may be, obtained.This arrangement also obviates the necessity of a voltage regulatingapparatus for the light source, because the balance of the photoelectriccell circuit is maintained regardless of the intensity of the lightsource itself.

In one common type of smoke detector for ducts, a hole is formed in oneside of the duct for the projection into the duct of a light beam, and ahole is formed in the opposite side of the duct for the insertion of aphotoelectric cell upon which the light beam is projected, so that smokein the duct will partially block passage of the light to the cell andconsequently energize the photoelectric cell circuit.

Systems of this character are complicated to install, requiring twoholes in the duct and separate handling and application to the duct ofthe photoelectric unit and the light source. Furthermore, it isdifllcult to obtain the desired sensitivity because of the necessity ofadjusting the photoelectric cells and the light source relatively toeach other at opposite sides of the duct.

Therefore one object of the present invention is to provide a novel andimproved smoke detecting unit which can be easily and quickly applied tothe duct and in which the photoelectric cell and light source can berelatively adjusted before the unit is mounted on the duct.

Another object is to provide such a unit which shall be uniformlysensitive, regardless of the width or shape of the duct.

A further object is to provide a novel and improved construction andcombination of parts whereby the unit shall be compact so as to requirea minimum of space and a minimum of handling of separate parts duringinstallation of the duct.

A still further object is to provide in apparatus of this character,anovel and improved construction and combination of light source,photoelectric balancing cell and means whereby the effect of the lightfrom the light source upon the balancing cell shall be capable of easyand accurate adjustment or control from the exterior of the unit andduct.

Other objects are to provide a novel and improved combination of aphotoelectric cell, a light shutter or baflle therefor whereby theefiectof the light on the cell can be varied, and means for mounting andadjusting the baflie or shutter from the outside of the unit by thesimple manipulation of a single element; and to obtain other advantagesand results that will be brought out by the following description inconjunction with the accompanying drawings wherein:

Figure 1 is a front perspective view of a smoke detecting unit andsignal embodying our invention, showing the unit mounted on a ductwhich.

is f ragmentarily illustrated.

Figure 2 is an enlarged front elevational view of the smoke detector andsignal unit with the front wall of the casing removed.

Figure 3 is a horizontal sectional view approximately on the plane ofthe line 3-3 of Figure 2.

Figure 4 is a transverse vertical sectional view approximately on theplane of the line 4-4 of Figure 3.

Figure 5 is a longitudinal-vertical sectional view approximately on theplane of the line 5-5 of Figure 3.

Figure 6 is a view similar to Figure 4 approximately on the line 6-6 ofFigure 3..

Figure 7 is a wiring diagram of the electrical circuit for the smokedetector and signal including a manual resetting apparatus for theSensitro or other relay; and

Figure 8 is a similar view showing a modified circuit for use where thesignals and resetting switch are to be remotely related to the detectorunit.

Specifically describing the illustrated embodiment of the invention, thesmoke detector unit comprises a casing which includes a base plate I anda removable box-like cover 2 that may be separably connected together inany suitable manner. Preferably, as shown, the base plate has projectingfrom one side thereof, a Z-shaped frame 3 which comprises a flange 4secured in any suitable manner to the base plate as by riveting,welding, soldering or the like; an intermediate portion 4a and anotherflange 5 pro- Jecting from said intermediate portion in the oppositedirection of the flange 4 and spaced in approximately parallel relationthereto.

The front or top wall 6 of the cover 2 is secured to the flange 5 in anysuitable manner as by screws 1. The'intermediate portion 4a of the framealso serves as a partition for dividing the casing into upper and lowercompartments 3 and 9, and for supporting some of the parts of the unit.As shown, an incandescent lamp I is mounted on one side of theintermediate section or partition 4a, as is also a series relay ll ofany suitable construction, the purpose of which will be hereinafterdescribed.

On the opposite side of the partition 41;, is mounted a Sensitrol orother suitable relay l2, said relay being mounted on one flange l3 of anL-shaped bracket, the otherarm M of which is connected to the partition4a.

Also'mounted on the second-mentioned side of the partition 4a, is apower relay of suitable known construction, and a U-shaped bracket l6for the balancing cell and its shutter mechanism is mounted on theflange 4.

The flange 5 of the frame 3 has mounted therein two signal lamps l1 and8, one of which serves as a smoke signal, while the other serves toindicate trouble in the system. The cover 2 has suitable ventilatingopenings or louvres IQ for circulation of air to prevent overheating ofthe unit from the lamp Ill.

In the base plate I, is a lens system 20 through which the rays from thelamp ID are directed outwardly from the casing in a substantiallyparallel beam. and on the side of the base plate opposite the frame 3 ismounted a photoelectric cell 2| at one side of the light beam so as tobe sensitive to light rays reflected from suspended matter in a fluid,such as smoke passing through the light beam.

This-cell may be mounted in any suitable manner but is shown assupported by screws 22 on one arm of an L-shaped bracket 23, the otherarm of which is separably secured as by screws 24 to the base plate.This photoelectric element may be of any suitable type, such as thecurrent generating barrier layer type, and preferably has a large fiatrectangular exposed light-sensitive surface 25, and is capable ofgenerating suflicient current to operate a Sensitro1" withoutamplification of the electricity. The light-sensitive surface is exposedin close proximity to the outer boundaries of the light beams and istilted obliquely with respect to the light beam so that said surface isinclined away from the light source as shown in Figure 3, wherebygreater sensitivity is obtained and the effect of stray light rays issubstantially reduced. By simply bending the bracket 23, the cell 2| maybe moved toward and away from the light beam and tilted with respectthereto as desired, the screws 22 also facilitating this. adjustment.

In accordance with the invention, the casing is mounted on one wall of aduct 26 which is to be protected by the detector and signal, with thelens system and the photoelectric cell 2| projecting into the duct asbest shown in Figures 2 and 4. The duct is formed with a suitableopening 2'! through which the lens system and the photoelectric cell maybe inserted, and the base plate of the unit may have any suitable meansfor attaching the casing to the duct, for example 'trically operateddevice such arms or ears 28 projecting laterally from the base plate andsecured to the duct by screws 29.

The photoelectric element 2| is connected in circuit with any suitableelectric responsive device, for example a micro-ammeter or, as shown, a"SensitroP l2, the face of which is exposed and visible through anopening 30 in the cover 2 of the casing. This Sensitrol controls anothercircuit which may include any desired elecas the signal lamp Anotherphotoelectric element 3|, which may be of the same general type as theelement 2|, is mounted by bolts 32 on a U-shaped bracket 33, one arm ofwhich is secured by bolts 34 to the flange 4 of the frame 3. Thelight-sensitive surface of said cell 3| faces upwardly toward and indiagonal relation to an opening 35 in the partition 4a so as to besubject to light rays passing from the light source I 0 through saidopening 35. Preferably a transparent or transluscent plate 36 isdisposed across the opening 35 to diffuse the light rays.

To vary the extent of exposure of the photoelectric element 3| to thelight rays, a shutter or baflle 31 overlies the light-sensitive surfaceof the cell and has connected thereto, preferably cast integrallytherewith, a nut 38 through which is threaded a screw 39, one end ofwhich is journaled in one arm 40 of the bracket 33, while its other endportion is rotatably mounted in a bearing 4| on the other arm of thebracket. The screw is held against longitudinal movement by means ofstop collars 42 fastened on the screw at opposite sides of the bearing4|, and for holding the screw in adjusted position. a compression springis interposed between-one of said collars 42 and a head 44 on the screwwhich is exposed through an opening 45 in the cover 2 and has suitablemeans such as a kerf 46 to facilitate rotation of the screw.

With this construction, it will be observed that by rotating the screw39, the shutter 31 will be moved in such a way as to expose more or lessof the light-sensitive surface of the cell 3|, as best shown in Figures5 and 6.

The photoelectric element 3| is connected in circuit with thephotoelectric element 2| and the "Sensitrol" |2 in what is known as an"opposed parallel arrangement, or so that the photoelectric effects ofsaid elements are caused to operate in compensating differential orexposed retric cell circuit is so adjusted that the relay or otherdevice l2 will assume a normal condition;

for example, to open the signal circuit when no is responsive throughthe electromagnetic coil 64 to current in the photoelectric cell circuitand normally spaced from a fixed contact 48, but is actuated intoengagement with said contact when the photoelectric cell circuit isenergized, as

shown in Figure 2.

When the Sensitrol is energized by electricity generated by thephotoelectric cell 2|, its contact arm 41 engages the contact 48 andtends to remain in such contact because of magnetic attraction of thelatter for the pointer as is well known in the art. It is customary toprovide means for resetting this contact arm either directly orindirectly from a remote point. As shown in Figure 2, the resettingmechanism includes two arms 49 which are pivoted to move toward eachother upon manual pressure exerted on a push rod 50, said arms 49 beingdisposed at opposite sides of the pointer, and when moved togetheractuating the pointer to its neutral position away from the contact 48.The arms 49 are actuated into normal inoperative position by springs 5|.All of this structure is old and well known and no claim thereto is madein this application.

In one form of remotely controlled resetting mechanism which isschematically illustrated in Figure 8, a push rod 52 is actuated by anelectromagnetic coil 53 controlled by a manually operated electricswitch so as to push the pointer 54 of the Sensitrol away from itscooperating fixed contact 55.

The photoelectric cells, light source, "Sensitrol and signals may beconnected in circuit in different ways, and one possible circuitarrangement is shown in Figure '7. A suitable source of current isprovided, for example a transformer 56 for stepping down house currentto say 22 volts, for operating the signal such as the lamp l1 or a gong51. One terminal of the source is connected to one terminal of the coil58 of a relay which includes a switch 59 that controls the circuitthrough a trouble lamp l8 and buzzer 61,. the other terminal of saidcoil 58 being connected through the exciter lamp ill to the otherterminal of the circuit. g

One terminal of the coil 62 of a power relay is connected to oneterminal of the source and has its other terminal connected through theSensitrol switch 4148 to the other terminal of the source. The icoil 62controls a relay switch 63 which is connected in circuit with thesmoke-indicating lamp l1.

With this construction, it will be understood that normally theSensitrol" switch 41-48 will be open, but when smoke enters the duct 26,the photoelectric cell circuit will be operated so as to energize theactuating coil 64 of the Sensitrol" and thereby close the switch 41-48.This in turn will cause energization of the power relay coil 62 whichwill close the switch 63 and enersize the smoke-indicating lamp 11.Should any 6 trouble arise in the circuit, for example should theexciter lamp l0 burn out, the series relay switch 59 will be opened soas to cause operation of the trouble lamp l8 and buzzer 6|.

In Figure 8, the circuit is similar, but the signal lamp 11, the troublelamp l8 and the gong 51 may be mounted at a remote point from thedetector unit, for example on an instrument board in the oflice of-afactory. Also, on such an instrument board may be mounted a manuallyoperated switch'lill for controlling the circuit through the coil 53 ofthe "Sensitrol resetting mechanism. The circuit includes the seriesrelay switch 5869 and the power relay switch 626 3 which perform thesame functions as they do in the circuit shown inFigure 7. A toggleswitch 65 is also mounted on the instrument board and connected incircuit for throwing the circuit into on and off positions.

From the foregoing it will be seen that my invention provides a smalland compact smokedetector and signal unit which can be easily andquickly applied to and removed from a duct, and wherein thephotoelectric cell may beproperly adjusted to provide the desiredsensitivity easily,

quickly and before the unit is mounted on the duct. Also, a simple andeasily operated means is provided for adjusting at will the balancingphotoelectric cell 3|.

It will be understood by those skilled in the art that thesmoke-detecting unit may be connected to the source of current in anysuitable manner, but for convenience I have adopted aplug coupling orconnector 66 to which may be connected a socket member on an electriccord or cable that in turn may be connected to the source ofelectricity, this separable plug connection facilitating the applicationand removal of the unit to and from the duct.

While I have shown and described the invention as embodied in certaincombinations of structural details, it should be understood that manymodifications and changes in the construction of the apparatus may bemade within the' spirit and scope of the invention.

, I claim:

ing in one wall thereof, and apparatus for detecting suspended matter influid flowing through said duct, said apparatus comprising a supportsecured upon the exterior of said duct wal1 and closing said openingagainst entry of light therethrough into the-duct, said support havingan apert-ure in register with said opening, a light source mounted onone side of said support and arranged to project a beam of light throughsaid aperture and said opening into said duct, and photoelectricmechanism including a photoelectric element mounted on the other side ofsaid support and projecting into said duct through said opening at oneside of said light beam so as to receive light rays reflected fromsuspended matter in said fiuid.

2. The combination as defined in claim 1 with the addition of a secondphotoelectric element mounted on the first mentioned side of saidsupport and subject to light from said source, means connecting saidphotoelectric elements in an electric circuit so that the photoelectriceffects of the second photoelectric element oppose the photoelectriceffects of the first-named photoelectric element, and an electricalresponsive means connected in said circuit.

3. A smoke detector of the character described comprising a casinghaving a base plate and a removable cover connected thereto, a partitionin said casing dividing it into two compartments, one of which has anaperture in its outer walls, a light source in the first-mentionedcompartment arranged to project a beam of light outwardly through saidaperture, a photoelectric element mounted exteriorly on said casing atone side of said aperture and having a light-sensitive surfaceapproximately parallel to said beam, a second photoelectric elementmounted in the other of said compartments, said partition having atransparency through which light from said source is projected upon saidsecond photoelectric element, means connecting said photoelectricelements in an electric circuit so that the photoelectric eifects of thesecond photoelectric element oppose the photoelectric effects of thefirstnamed photoelectric element, and an electrical responsive meansconnected in said circuit.

4. A smoke detector of the character described comprising a casinghaving a base plate and a removable cover connected thereto, a partitionin said casing dividing it into two compartments, one of which has anaperture in its outer walls,

- a light source in the firstementioned compartment arranged to projecta beam of light outwardly through said aperture, a photoelectric elementmounted exteriorly on said casing at one side of said aperture andhaving a light-sensitive surface approximately parallel to said beam, 9.second photoelectric element, said partition having a transparencytherein, a U-shaped bracket on the base of which said secondphotoelectric element is mounted, means connecting one arm of saidbracket to said base plate in the other compartment so that said secondphotoelectric element is subject to light rays from said source thatpass through said transparency, a shutter overlying said light-sensitivesurface of said second photoelectric element, and means mounted in thearms of said bracket for adiusting said shutter to vary the extent ofexposure of said light-sensitive surface to said light rays.

5. The smoke detector as defined in claim 4 wherein the last-named meansincludes a nut fixed on said shutter and a rod rotatably butnonlongitudinally movably mounted in said arms of said bracket andhaving a screw-threaded connection with said nut.

6. Apparatus for detecting suspended matter in fluid flowing through aduct having an openingin one wall thereof comprising a supportconstructed to be secured upon the exterior of the duct and closing theduct wall opening against the entry of light from around the support,the support having an aperture in register with said opening, a lightsource mounted on one side of said support and arranged to project abeam or light through the said aperture and said opening into the duct,and photoelectric mechanism including a photoelectric element mounted onthe other side of said support and arranged to extend into the ductthrough the opening at one side of said light beam so as to receivelight rays reflected from suspended matter in said fluid.

7. The combination as defined in claim 6 with the addition of a secondphotoelectric element mounted on the first mentioned side of saidsupport and subject to light from said source, means connecting saidphotoelectric elements in an electric circuit so that the photoelectriceffects of the second photoelectric element oppose the photoelectriceifects of the first-named photoelectric element, and an electricalresponsive means connected in said circuit.

8. A smoke detector for detecting suspended matter in fluid flowingthrough a duct having an opening in one wall thereof comprising asupport constructed to be secured upon the exterior of the duct andclosing the duct wall opening against the entry of light therethroughinto the duct, the support having an aperture therein in alignment withthe opening in the duct, a light source carried by the support toproject a beam of light outwardly through the aperture, and aphotoelectric element mounted on said support and shielded therebyagainst direct rays of light from the light source, the photoelectricelement having a light-sensitive surface extending approximatelyparallel to the beam of light, a, second photoelectric element carriedby the support and subject to light from the source transmitted otherthan through the fluid being tested,.means connecting the photoelectricelements in an electric circuit so that the photoelectric efiects of thesecond photoelectric element oppose the photoelectric effects of thefirst-named photoelectric element, and an electrical responsive meansconnected in said circuit to indicate the presence of smoke in the fluidbeing tested.

CLARENCE NOEL CAHUSAC.

REFERENCES orrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,167,045 Cade et a1 Jan. 4, 19161,828,894 Freygang Oct. 27, 1931 2,032,746 Grant, Jr Mar. 3, 19362,165,054 Johnson July 4, 1939 2,301,367 Cahusac et al. Nov. 10, 1942

